Data communication method and data communication system using data communication apparatus therein

Abstract

The data communication system according to the present invention executes data transmissions and data receptions between a main unit and a plurality of terminals by the polling/selecting method. The main unit comprises a key input section and a memory that stores information on communication periods of each terminal, which were set by using the key input section. In a case where polling/selecting is performed, the communication periods of the designated terminal are read. The main unit further comprises a timer. The present time which is read from the timer is compared with the designated communication periods which are read from the memory and whether or not the present time is within the communication periods is determined. In the case where the time is within the communication periods, the main unit executes the polling/selecting processing to the terminal and the data communication is performed. On the other hand, in the case where the time is out of the designated communication periods, the main unit does not perform any processing to the terminal. The above-described processes are sequentially executed to each of the plurality of terminals.

What is claimed is: 
     
       1. A data communication apparatus which performs data communications with a plurality of terminals, comprising: reception means for receiving, from the plurality of terminals, a plurality of informations each indicating a time period when each of the plurality of terminals may be accessed;   storage means for storing the plurality of informations received by the reception means as communication periods of the plurality of terminals, respectively;   timer means for measuring a present time;   discrimination means for discriminating whether or not the present time is contained in each of the communication periods, stored in the storage means, of the plurality of terminals; and   communication means for executing the data communication with each of the plurality of terminals whose communication period is discriminated, by the discrimination means, to contain the present time.   
     
     
       2. The data communication apparatus according to claim 1, wherein the communication means executes a data communication by the polling method with each of the plurality of terminals whose communication period is discriminated to contain the present time by the discrimination means. 
     
     
       3. The data communication apparatus according to claim 1, wherein the communication means executes a data communication by the selecting method with each of the plurality of terminals whose communication period is discriminated to contain the present time by the discrimination means. 
     
     
       4. The data communication apparatus according to claim 1, wherein the communication means executes a wireless data communication with each of the plurality of terminals whose communication period is discriminated to contain the present time by the discrimination means. 
     
     
       5. The data communication apparatus according to claim 1, wherein the reception means checks whether or not a received information is the information indicating a time period when any one of the terminals may be accessed. 
     
     
       6. The data communication apparatus according to claim 1, wherein the discriminating means reads out the communication periods from the storage means one after another, and discriminates whether or not the present time is contained in the read out communication period. 
     
     
       7. The data communication apparatus according to claim 1, wherein each of the time periods is set at the plurality of terminals, respectively and an information indicating the set time period is transmitted to the data communication apparatus from each of the plurality of terminals. 
     
     
       8. The data communication method which performs data communication with a plurality of terminals, comprising the steps of: receiving, from the plurality of terminals, a plurality of information each of which indicates a time period when each of the plurality of terminals may be accessed;   storing the plurality of informations received by the receiving step as communication periods of the plurality of terminals, respectively;   measuring a present time;   discriminating whether or not the present time is contained in each of the communication periods, stored by the storing step, of the plurality of terminals; and   executing the data communication with each of the plurality of terminals whose communication period is discriminated, by the discriminating step, to contain the present time.   
     
     
       9. The data communication method according to claim 8, wherein the communication step execute a data communication by the polling method with each of the terminals whose communication period is discriminated to contain the present time by the discriminating step. 
     
     
       10. The data communication method according to claim 8, wherein the communication step executes a data communication by the selecting method with each of the terminals whose communication period is discriminated to contain the present time by the discriminating step. 
     
     
       11. The data communication method according to claim 8, wherein the communication step executes a wireless data communication with each of the terminals whose communication period is discriminated to contain the present time by the discriminating step. 
     
     
       12. The data communication method according to claim 8, further comprising a step of checking whether or not a received information is the information indicating a time period when any one of the terminals may be accessed. 
     
     
       13. The data communication method according to claim 8, further comprising a step of reading out the stored communication periods one after another, and the discriminating step discriminates whether or not the present time is contained in the read out communication period. 
     
     
       14. The data communication apparatus according to claim 8, wherein each of the time periods is set at the plurality of terminals, respectively and an information indicating the set time period is transmitted to the data communication apparatus from each of the plurality of terminals.